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Jan. l, 1963
F. E. DAVIS, JR., ET AL
3,071,542
TWO STAGE PRETREATMENT oF REFORMER CHARGE NAPHTHA
Filed July 16, 1958
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Jan. l, 1963
F. E. DAVIS, JR., ET AL
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TWO-STAGE PRETREATMENT OF REFORMER CHARGE NAPHTHA
Filed July 16, 1958
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Jan. 1, 1963
F. E. DAVIS, JR., ET AL
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TWO-STAGE PRETREATMENT OF' REFORMER CHARGE NAPHTHA
Filed July 16, 1958
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Jan. l, 1963
F. E. DAVIS, JR., ETAL
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TWO-STAGE PRETREATMENT OF REFORMER CHARGE NAPHTHA
Filed July 16, 1958
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Jan» l, 1963
F. E. DAvls, JR., ETAL
3,071,542
TWO‘STAGE PRETREATMENT OF REFORMER CHARGE NAPHTHA
Filed July 16, 1958
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United States Patent Oiilìce
3,07L542
Patented dan. 1, 1963
2
1
It has now `been determined that when a naphtha having
3,071,542
a high nitrogen content, i.e., in excess of 25 ppm. of nitro
gen is first hydrodecontaminated under relatively mild
Francis Earle Davis, Jr., Westville, and Amilcare Ramella,
Woodbury, NJ., assignors to Socony Mobil Oil Com
ticularly as `described hereinafter, the treated na-phtha
TWG-STAGE PRETREATMENT 0F REFORMER
CHARGE NAPHTHA
conditions such as set forth hereinbefore and more par
stripped of volatile nitrogen compounds, and the stripped
treated naphtha mixed with low nitrogen containing naph
pany, inc., a corporation of New York
Filed July 16, 1958, Ser. No. 748,901
7 Claims. (Cl. 203-254)
tha to provide a blend having not more than about 7 ppm.
and the mixture hydrodecontarninatedunder relatively
The present invention relates to the pretreatment of
naphtha to be reformed over a nitrogen-sensitive catalyst
and, more particularly, to the pretreatment of naphtha
miid conditions as set -forth hereinbefore and more par
ticularly `as described hereinafter, the hydrodecontami
nated mixture will contain less than 1 ppm. of nitrogen.
containing nitrogen compounds under relatively mild con
illustrative of the treatment of a high nitrogen naphtha
ditions prior to reforming the pretreated naphtha over a
containing in excess of 25 ppm. of nitrogen is the ilow
nitrogen-sensitive catalyst of the platinum type.
15 sheet of FIGURE 1. The flowsheet of FIGURE l illus
For several yea-rs it has been common practice to hydro
trates the treatment of a naphtha having a high concentra
tion of nitrogen, to wit: Thermal naphtha containing 66
desulfurize naphtha prier to reforming the naphtha. In
some instances the hydrodesulfurization of the naphtha
ppm. of nitrogen, over a catalyst combining capabilities
was to eliminate poisoning of the reforming catalyst but
of hydrogenate, hydrodesulfurize and hydrodenitrogenize,
in most instances the hydrodesulfurization of the naphtha 20 e.g., a mixture of oxides of cobalt and molybdenum. The
was to reduce corrosion of the reforming unit or to reduce
partially hydrodecontaminated na-phtha is stripped of vola
the size of the facilities required to remove the sulfur
tile hydrogen `derivatives of the contaminants, and the
compounds from gases vented to the air.
stripped, partially hydrodecontaminated naphtha `contain
rior to the increased demand for high octane gasoline
ing about 24 ppm. of nitrogen is then mixed with a naph
it Was unnecessary to reform many stocks containing high 25 tha having a low nitrogen content, eg., about 0.2 ppm.
concentrations of organic nitrogen compounds which
to provide a mixture containing about 3 ppm. of nitrogen.
poison nitrogen-sensitive catalysts such as the platinum
type reforming catalysts. With the increased demand for
The mixture is hydrodecontarninated and stripped of vola
tile hydrogen derivatives of the contaminants to provide a
high octane gasoline it has become necessary to reform
many of those stocks Which until recently were not re
formed.
reformer feed containing about 0.3 ppm. of nitrogen and
30 less than >20 ppm. of sulfur. The naphtha feed thus pro
duced is then reformed over a nitrogen-sensitive catalyst,
e.g., a platinum-type catalyst comprising about 0.1 to
thas can be carried out under relatively mild conditions of
'about l percent platinum on alumina.
temperature, pressure and hydrogen-to-naphtha ratio and
In FÍGURE l a naphtha containing in excess of 25
at a relatively high space velocity. Thus, for example, a 35 ppm. of nitrogen, e.g., thermal naphtha containing about
straight run naphtha from a Kuwait crude containing
66 ppm. nitrogen, is drawn from a source not shown
about 800 parts per million (ppm.) of sulfur and 0.2
through pipe 'l by pump 2. Pump 2 discharges: the thermal
ppm. of nitrogen can be hydrodesulfurized and hydrode
naphtha containing about y66 ppm. of nitrogen into con
nitrogenized over a catalyst comprising a mixture of oxides
duit 3 at -a pressure in excess of the pressure in secondary
of cobalt and molybdenum on alumina at about ‘675° F. 40 decontaminator 10. It is preferred to mix .about 50 to
under about 425 psig. at a hydrogen-to-naphtha ratio of
about 100 cubic feet (c_f.) of hydrogen per barrel of ther
about 500 standard cubic feet (scf.) of hydrogen per
mal naphtha with the naphtha prior to heating the naph
barrel of naphtha charged and at a space Velocity (volume
tha to hydrodecontaminating temperature. Accordingly,
of naphtha/hour/volume of catalyst, v./hr./Y.) of about 45 hydrogen-rich recycle gas flowing from conduit 9` under
5 to provide a reformer charge stock containing less than
control of valve 84- flows through conduit S5 to `conduit; 3i.
20 ppm. sulfur and substantially devoid of nitrogen com
The mixture of thermal naphtha and the small amount of
pounds. On the other hand, when a mixture comprising
hydrogen ltlows through conduit 3 to heat exchanger 4
about 15 percent by volume of thermal gasoline con
where the thermal naphtha is in indirect heat exchange
taining 66 ppm. of nitrogen `and about 85 percent by 50 relation with the effluent of the secondary decontaminator
volume of straight run naphtha containing about 0.2 ppm.
l0 flowing through conduit 11.
‘
‘
`
’
of nitrogen is hydrodecontaminated over the same catalyst
From heat exchanger 4 the thermal naphtha and the
under the same operating conditions the nitrogen content
small amount of hydrogen flow through conduit 5 to coil
of the hydrodecontaminated mixture is reduced from l0
6 in heater 7. In coil 6 the thermal naphtha is heated to
ppm. to 1.4 ppm.
55 a hydrodecontaminating temperature Within the range of
It has been found that to maintain 4a platinum-type re
about 600° to about 85 0° F. The heated thermal naphtha
forming catalyst on stream for a practical period of time
and hydrogen flow from coil 6 through conduit 8 to con
the nitrogen content of the charge to the reforming re
duit 9. In conduit 9 the thermal naphtha is mixed with
Hydrodesulfurization of practically lall common naph
actor must be less than about l p.p.m. of nitrogen.
additional hydrogen to provide a total of about 50() to
It has also been `determined that to reduce the nitrogen 60 about 2500 scf. of hydrogen per barrel of thermal naph
content of a naphtha containing about 12` ppm. of nitro
tha. For this purpose hydrogen-rich gas drawn from
gen to less than 1 ppm. of nitrogen requires much more
liquid-gas separator 17 and stripper 24 by compressor 29
severe conditions than the aforedescribed mild condi
as hereinafter `described and `discharged into conduit 9 is
tions. Thus, a naphtha containing l2 ppm. of nitrogen
can be hydrodecontaminated to a nitrogen content of less 65
than 1 ppm. over a catalyst comprising a mixture of
oxides of cobalt and molybdenum on alumina at a tem
perature of 775° F., pressure of 425 p.s.i.g., hydrogen-to
naphtha ratio of about 2000 s.c.f./ barrel of naphtha
charged and a space velocity of 2.
used. The heated thermal naphtha and hydrogen-contain
ing gas flow through conduit 9 to secondary decontami
nator 10.
`
In secondary decontaminator 10 the treating condi
tions for a cobalt `molybdenum ycatalyst are Within the
limits set `forth in Table I.
3,071,542
4
.
v
Table I
Catalyst: 2 to 3A percent cobalt oxide, 9 to 16 percent molyb
denum oxide on alumina.
Feed: Thermal naphtha containing 66 ppm. nitrogen.
Broad
Temperature, ° F_.
60G-850
suction side of compressor 29. Any gas in excess of that
Preferred
675-775
Pressure p.s.i.g_ _ __
20G-1, 000
400-800
S.e.f, 11g/barrel of naphtha 1_-.
50S-2, 500
SOO-1,000
1-10
2. 5-5
Space velocity, v./hr./v ______________________ __
From means 2,7 the purified gaseous mixture designated
secondary recycle gas and containing about 50 to aboutv
95 percent hydrogen ilows through conduit 28 to the
required in the secondary decontaminator is vented from
conduit 28 through conduit 30 under control of valve
31 for use in other processing or to the reñnery fuel sys
tem. Compressor 29 discharges the secondary recycle
gas into conduit 9 as described hereinbefore.
Returning now to stripper 24; the stripped secondary
condensate forms a bottoms in stripper 24.
1 Sci. is standard cubic feet.
The thermal naphtha and hydrogen-containing recycle
gas pumped from separator 17 and stripper 24 by com
A minor
portion of the bottoms of stripper 24 iiows from stripper
24 through pipe 32 to heat exchanger 33 and from heat
exchanger 33 through pipe 34 back to stripper 24. In
pressor 29 at a pressure higher than that in the second
heat exchanger 33 the bottoms is heated to a tempera
ary decontaminator 10 flow downwardly through the
ture at which under conditions in the stripper Z4 the
secondary decontaminator to conduit 11. The partially
hydrogen derivatives of the contaminants originally
decontaminated thermal naphtha and recycle gas, here
present in the thermal gasoline are volatilized. Any other
inafter designated second-ary etiluent, ilow through con
Vmeans for maintaining the necessary stripping tempera
duit 11 to heat exchanger 4 where the secondary effluent 20 ture can be used instead of the reboiler shown.
is in indirect heat exchange relation with the thermal
The major portion of the stripper bottoms ilows from
naphtha feed as described hereinbefore.
stripper 24 through pipe 35 to the suction side of pump
The secondary eñluent Hows from heat exchanger 4
36. Pump 3'6 discharges the bottoms of stripper 24 into
through conduit 12 to heat exchanger 13 where the sec
pipe 37.
ondary eñluent is in indirect heat exchange relation with 25 The bottoms of stripper 24 usually contains not more
the secondary condensate pumped from liquid-gas sep
than about 140 p.p.m. of nitrogen. In the illustrative
arator 17 by pump 21 through pipe 22. The cooled
case in which the thermal naphtha feed contained 66
secondary eflluent flows from heat exchanger 13 through
p.p.m. of nitrogen and 1,700 p.p.m. of sulfur the stripper
conduit 14 to cooler 15 Where the temperature of the
bottoms contained about 24 ppm. of nitrogen and about
second-ary eñiuent is lowered to that at which C4 and 30 82 p.p.m. of sulfur.
heavier hydrocarbons are liquid at the pressure existing
Prior to treatment in the primary decontaminator the
in liquid-gas separator 17.
stripper bottoms is mixed with a low nitrogen naphtha
From cooler 15 the secondary effluent ñows through
such as a straight run naphtha containing about 0.1 to
conduit 16 to liquid-gas separator 17. In liquid-gas sep
about l ppm. of nitrogen. In the illustrative case a
arator 17 the uncondensed portion of the secondary efllu 35 straight run naphtha containing about 0.2 ppm. of nitro
ent separates from the condensed portion of the second
gen was mixed with the bottoms of stripper 24 in pro
ary eñluent. The uncondensed portion of the secondary
portions to provide a primary decontaminator feed con
eñluent flows from separator 17 through conduit 18 to
taining not more than about 7 ppm. of nitrogen. In
conduit 19.
-
the illustrative case the stripper bottoms and straight run
The condensed portion of the secondary eiïluent ñows 40 naphtha were mixed in the proportions indicated in
through pipe 20 to pump 21. Pump 21 discharges the
Table II.
condensed portion of the secondary effluent, hereinafter
Table II
designated secondary condensate, into pipe 22 through
which the secondary condensate ñows to heat exchanger
Percent
P.p.m.
by
Ppm. Nitrogen
13 where it is in indirect heat exchange relation with 45
Volume Nitrogen
in
the secondary eñluent. From heat exchanger 13 the
Mixture
secondary condensate ñows through pipe 23 to stripper 24.
The secondary condensate is stripped of volatile hydro
Stripper bottoms _____________________ __
15
24
3. 6
Straight run raphtha _________________ _ _
85
0. 2
. 17
gen derivatives of the contaminants sulfur, nitrogen,
arsenic, etc., originally present in the thermal naphtha in 50
Total
_
_
3. 77
stripper 24. Preferably a stripping gas eg., hydrogen
containing gas from the primary liquid-gas separator S3
Accordingly, straight run naphtha drawn from `a source
and/or the primary stripper 60 and/or recycle gas from
not shown through pipe 38 by pump 39 is pumped through
a reformer unit flowing'through conduit 74 as more fully
pipe ‘40 to heat exchanger 41. In heat exchanger 41 the
discussed hereinafter is used to assist in’stripping the 55 straight run naphtha is in indirect heat exchange relation
volatile hydrogen derivatives of the contaminants present
with primary effluent flowing from primary decontami
in the thermal naphtha feed from the secondary con
nator 46 through conduit 47. From heat exchanger 41
densate. The volatile hydrogen derivatives of the afore
the straight run naphtha ilows through pipe 42 to pipe 37
said contaminants, together with light hydrocarbons and
where it is mixed with the stripper bottoms to provide a
stripping gas are taken as overhead through conduit 19. 60 mixture containing about 50 to about 95 percent by
The overhead from stripper 24 flows through conduit 19
Volume straight run naphtha, said m-ixture containing
and together with the uncondensed portion of the second
not more than about 7 ppm. of nitrogen. The mixture
ary eñiuent flowing from separator 17 through conduit
of stripper bottoms and straight run naphthia, hereinafter
18 (as described hereinbefore) Hows to any suitable means
designated primary decont-aminator feed flows through
25 for removing the hydrogen derivatives of nitrogen 65 pipe 37 `to coil 43 in heater 44. It is preferred to mix
compounds originally present in the thermal naphtha, to
a small amount, say about 50 to about 100 s.c.-f. of
wit, ammonia. For example, the gaseous mixture can
hydrogen-containing gas such as primary recycle gas
be contacted with aqueous acid, for example, sulfuric
pumped yby compressor 67 through conduits 68 and 69
acid, to remove the ammonia. From the means 25 to
remove ammonia the gaseous mixture ilows through con 70 under control `of valve 70 with the primary decontamina
tor feed prior .to heating the primary decontaminator
duit 26 to means 27, such as an amine scrubber, for re
moving hydrogen sulñde (the hydrogen derivative of sul
fur compounds originally present in the thermal naphtha).
feed to reaction temperature. The prim-ary decontamina
tor feed and primary recycle gas are heated in
Hydrogen sulfide removal means 27 can be by-passed by
heater 44 to a temperature within the range of about
closing valve 86 and opening valve 88 in conduit 89. 75 600 to about 850° F. From coil 43 the primary decon
3,071,542
6
taminator feed .and hydrogen flow through conduit 45 to
primary decontaminator 46. In conduit 45 additional
hydrogen-containing gas, such as primary recycle gas,
pumped by compressor 67 through conduit 68 is mixed
with the primary decontaminator feed in amount suffi
conduit di to means for removing hydrogen sulfide 65,
for example, an amine scrubber.
From the means for
removing hydrogen sulfide 65 the primary recycle gas
iioWs to the suction side of compressor 67. Compressor
67 discharges the hydrogen-containing primary recycle
cient to provide a total of about 250 to about 1000 s.c.f.
gas into conduit 63. A small portion, say about 50 to
of hydrogen per barrel of primary decontaminator feed.
about 100 scri., of primary recycle gas is diverted through
The mixture of primary decontaminator feed and primary
recycle gas ilows downwardly through primary decontami
conduit 69 under control of valve "ïtl‘ to conduit 37 for the
purpose of mixing the primary recycle gas with the pri
10 mary decontaminator feed as described hereinbefore.
nator ¿t6 to conduit (i7.
The operating conditions in primary decontaminator
The balance of the primary recycle gas iiows through
conduit 6@ to conduit ¿i5 Where it is mixed with the pri
mary decontaminator feed in amounts to provide a total
`of about 250 to >about 2500 stof. of hydrogen per barrel
catalyst having hydrogenating as Well as decontaminating
capabilities such as a catalyst comprising about 3 percent 15 of primary decontaminator feed as described herein
46 are substantially the same as in second-ary decontami
nator lo and are mild operating conditions. For a
cobalt oxide and about 12 percent molybdenum oxide
on alumina the operating conditions in primary decon
before.
taminator 46 are as set forth in Table HI.
the »secondary `decontaminator condensate is either a por
tion of the overhead from stripper 6o or reformer recycle
Table III
As stated hereinbefore, the stripping gas for stripping
20 gas or -a mixture of both.
Catalyst: 2 to 3% cobalt oxide, 9 to 16% molybdenum oxide.
Feed: not more than 7 ppm. of nitrogen.
Broad
Preferred
Thus, when overhead from
stripper 60 is to be used to strip the secondary decontami
nator condensate in stripper 24 about 300 to about 500
s.«c.f. of overhead from stripper 6G per barrel of high
nitrogen feed naphtha flows from conduit 55 through con
duit '71’ under control of valve 77; to compressor 73.
Temperature, ° F _________________________ „_
Pressure, psig ________________ ._
600 to 850
200 to 1,060
675 to 775
400 to 500
Hydrogen, soil/bbl. of naphtha.-
250 to 2,500
400 to 600
1 to 10
2.5 to 5.0
Space Velocity, v./nr,/v ___________________ __
Compressor
ydischarges the overhead from stripper 60
yhereinafter designated secondary stripping gas into con
duit 74. The secondary stripping gas ñows through con
duit 7i to stripper 24. When it is necessary or desirable
From primary deeontaminator 45 the eilluent, desig 30 to use reformer recycle gas as stripping gas the required
nated primary effluent hereinafter, flows through conduit
amount of reformer recycle gas is «diverted from conduit
47 to heat exchanger 4i Where the primary eiiiuent is in
6l through conduit 75 under control of valve 76 to con
indirect heat exchange relation with the straight run
duit 7d through which the reformer recycle gas ilows to
naphtha as previously described. From heat exchanger
stripper Zái. lt follows that a ‘mixture of secondary strip
¿il the primary effluent flows through conduit 48 to heat 35 ping gas from conduit 55 and reformer recycle gas can
exchanger 49 where the primary effluent is in indirect heat
be used to strip Ithe secondary decontaminator conden
exchange relation With the condensed portion of the
sate in stripper 2d by opening both valves 76 'and 72 the
primary eñiuent designated primary condensate ñowing
required amounts to proportion secondary stripping gas
from liquid~gas separator 53. From heat exchanger 49,
yand reformer recycle gas las is necessary or desirable. In
the primary eñiuent ñows through conduit 50 to cooler 5l. 40 the event that either secondary stripper 24 or primary
ln cooler Si the primary eñ'luent is cooled to «a tempera~
ture at which C4 and heavier hydrocarbons condense
stripper d@ operates or both operate at pressures higher
than that `at which reformer recycle gas is available the
pressure of the reformer recycle gas can be raised to that
of stripper 2tl- Without raising the pressure of the re
at the pressure existing in liquid-gas separator 53. The
cooled primary effluent hows from heat exchanger 51
through conduit 52 to liquid-gas separator S3. In liquid 45 former recycle gas flowing to stripper 60 by opening valve
gas separator 53 the uncondensed por-tion `of the primary
77. The portion of the reformer recycle gas required in
effluent separates from the condensed portion of the pri
stripper 2d is `diverted under control of valve 77 through
mary effluent (hereinafter designated primary conden
conduit ‘78 to the suction side of compressor 79'. Com
sate) and flows from separator ‘53 through conduit 54 to
pressor '79 discharges `into conduit Si?. With valves S3
conduit 55.
50 and 76 closed, the portion of the reformer recycle gas
The primary condensate ilows from separator 53
diverted to compressor 7 9 ñows from conduit 80 to con
through pipe `5t to the suction side of pump 57. Pump 57
duits 7S and 74 to stripper 24. When both stripper 60
discharges the primary condensate into pipe 58 through
and [stripper 2d are operating `at pressures higher than
Which the primary condensate flows to `heat exchanger
that iat which the reformer recycle gas is available valve
49. In heat exchanger 49 the primary condensate is in 55 8l is closed, valve 77 is opened and the total flow of re
indirect heat exchange relation with the primary eñiuent
former recycle gas is passed through conduit 78 to com
pressor 79. With valve 83 open and valve 76 closed the
as hereinbefore described. From heat exchanger 49 the
primary condensate flows through pipe 59 to stripper 60.
discharge o-f `compressor 79 flows through conduits 61,
In stripper 60 the primary condensate is stripped of
30 and SZ lto stripper e0 and through conduits 80, 75 and
hydrogen derivatives of contaminants present in the pri 60 "74 «to `stripper 24.
mary feed, light hydrocarbons and residual hydrogen,
The flowsheet, FIGURE 2, illustrates another embodi
rnent `of the present invention wherein the secondary con
preferably with aid of a stripping gas such as hydrogen*
densate is freed from a major portion, if not all, of the
containing gas, for example, reformer recycle gas, pumped
ammonia produced in hydrodecontaminating a naphtha
from a reformer unit not shown through conduit 651. An
having a high nitrogen content, i.e., in excess of 25 ppm.
overhead comprising the hydrogen derivatives of con
of nitrogen.
taminants present in the primary feed such as ammonia
Thu-s, a hydrocarbon mixture such as a thermal naph
and hydrogen sulfide, hydrogen and light hydrocarbons,
th-a, eig., »a coker naphtha containing in excess of 25
hereinafter designated primary recycle gas, is taken from
ppm. of nitrogen is drawn yfrom a source not shown by
stripper 60 through conduit 62 to conduit 55. The over
head flows through conduit 55 to means 63 `of any suit 70 pump lill lthrough pipe to2. Pump 101 discharges the
hydrocarbon mixture containing in excess of 25` ppm.
able type, as for example contact With aqueous acid solu
t-ion, for removing ammonia. Hydrogen sulñde removal
means 6'5 can be bypassed by closing valves 90 and 91
and opening valve 92 in conduit 93. From the means
of nitrogen, hereinafter designated nitrogenous hydrocar
bon mixture, into pipe HB3. The nitrogenous hydrocar
bon mixture flows through pipe w3 to heat exchanger
63 for removing ammonia, the overhead ñows through 75 104 Where it is in indirect heat exchange relation With the
3,071,542l
7
8
effluent from the secondary decontaminator, hereinafter
designated secondary effluent, flowing from secondary de
and to an absorber Where the overhead is contacted with
nitrogenous hydrocarbon mixture prior to introduction
hydrocarbons to be decontaminated.
A portion of the bottoms of stripper 124 flows through
pipe 128 to heat exchanger 129 where the bottoms is
heated to a temperature at which a major portion of the C4
hydrocarbons is volatile. Any other means of maintain
ing the aforesaid temperature in stripper 124 can be used.
From heat exchanger 129 the bottoms flows through pipe
130 back to stripper 124.
The balance, and major portion, of the bottoms of strip
of the nitrogenous hydrocarbon mixture into coil 106.
per 124 containing not more than about 140 ppm. of
From heater 107 the heated nitrogenous hydrocarbon
mixture flows through pipe 108 to secondary decontami
nitrogen Hows therefrom through pipe `131 to the suction
side of pump 132. Pump 132 discharges the stripper
contaminator 110 through conduit 111.
From heat ex
changer 104 the niitrogenous hydrocarbon mixture flows
through pipe 105 to coil 106 in «furnace 107 where it is
heated to reaction temperature as described hereinbefore.
When desirable, a small amount, say about 50-100 scf.
per barrel, of hydrogen-containing gas, eg., primary re
cycle gas tiowing in conduit 109 can be mixed with the
nator 110.
At some point in pipe 108 intermediate to
heater 1117 and to decontaminator 110 hydrogen-contain
ing gas containing not more than about 0.02 percent
ammonia, eg., primary recycle -gas ñowing `from separa
tor 147 through conduits 14d and 149 to means for re
bottoms into pipe 133. At some point in pipe 133 inter
mediate to- pump 132 and to coil 134 in heater 13S a
hydrocarbon mixture having a nitrogen concentration such
that, when mixed with the aforesaid stripper bottoms in
the proportion of 50 to 95 parts -by volume to S0 to 5
parts by volume of stripper bottoms, the mixture has a
moving ammonia 159 and `thence through conduit 109
to pipe 10S is mixed with the nitrogenous hydrocarbon 20 nitrogen concentration of not more than about 7 ppm.,
mixture in an »amount to provide about 500 to about
is mixed With the stripper bottoms. A suitable low nitro
2500 s.c.f. of hydrogen per barrel of nitrogenous hydro
gen hydrocarbon mixture is straight run naphtha contain
ing about 0.2 ppm. of nitrogen. Accordingly, straight
carbon mixture.
The mixture of ‘hydrogen-containing `gas and nitrog
run naphtha, for example, is drawn from a source not
enous hydrocarbon mix-ture ñows downwardly through 25 shown through pipe 160 by pump 161 and pumped through
second-ary decontaminator 110. The secondary etñuent
pipe 162 to heat exchanger 141. In heat exchanger 141
«flows from secondary decontaminator 110 through con
the straight run naphtha is in indirect heat exchange rela
duit ‘111 to heat exchanger 104 where the secondary ef
tion with the efñuent from primary decontaminator 139.
fluent is in indirect heat exchange relation with the nitrog
The eflìuent from primary decontaminator 139, herein
eno-us hydrocarbon mixture as described hereinbefore. 30 after designated primary effluent, flows from decontamina
From heat exchanger 104 lthe secondary efliuent flows
tor 139 to heat exchanger 141 through conduit 140. The
Athrough conduit 112 to heat exchanger 113 where the sec
straight run naphtha ñows from heat exchanger 141
ondary eiiluent is in indirect heat exchange relation with
through pipe 172 to pipe 133 where the straight run
the condensate drawn from gas-liquid separator 117
naphtha is mixed with the stripper bottoms in a proportion
through pipe 120 hy pump 121 »and discharged into pipe
to provide a mixture having a nitrogen content not greater
122.
From heat exchanger 113 Kthe secondary effluent p
ñows :through pipe 114 to cooler (condenser) 115 Where
than about 7 ppm.
'
The mixture, of stripper bottoms and straight run naph
the `secondary effluent is cooled to a temperature at which
tha, containing not more than about 7 ppm. of nitrogen,
at the existing pressure the C4 and heavier hydrocarbons
hereinafter designated primary mixture, ñows through
are condensed. The cooled secondary efl'luent liows from 40 pipe 133 to coil 134 in heater 135. The primary mixture
cooler 115 through conduit 116 to gas-liquid separator
is heated in coil 134 to a reaction temperature as set forth
117.
hereinbefore of about 600° to about 850° F. (Table III).
In separator 117 the uncondensed portion of the sec
From coil 134 the heated primary mixture ñows through
conduit 136 to primary decontaminator 139. At some
ondary eñiuen-t comprising ammonia, hydrogen sulfide,
C3 land lighter hydrocarbons, and hydrogen separates 45 point in conduit 136 intermediate to heater 135 and to
from the condensed portion of the secondary effluent
primary decontaminator 139 hydrogen-containing gas, for
and ñows through conduit 11S to conduit 119 and thence
example, reformer gas is mixed with the primary mixture
to means :for removing ammonia 168 Iand thence through
to provide about 250 to about 25010 s.c.f. of hydrogen per
conduit 169 to means for removing hydrogen sullide (not
‘barrel of primary mixture. The primary mixture and hy
shown) and thence to an absorber (not shown) Where 50 drogen-containing gas flow downwardly through primary
the uncondensed secondary effluent is contacted with hy
decontaminator 139 in contact with a catalyst having
drocarbon mixture to be hydrodecontaminated. The con
capabilities to hydrogenate and dehydrosulfurize and de
densed portion of the secondary efñuent, hereinafter
hydrodenitrogenize the primary mixture. Illustrative of
designated »secondary condensate, flows from separator
such catalysts is that described hereinbefore. The efñuent
117 through pipe 12o to the suction side of pump 121.
from primary decontaminator 139, hereinafter designated
Pump 121 discharges «the secondary condensate into pipe
primary eiiiuent, flows through conduit 140 to heat ex
122. rl`he secondary condensate ñows through pipe 122
changer 141 Where it is in indirect heat exchange relation
to heat exchanger 113 as `described hereinbefore. From
with the straight run naphtha as previously described here
heat exchanger 113 the «secondary condensate, heated to
in. From heat exchanger 141 the primary etiluent flows
a temperature at which C4 and lighter hydrocarbons are 60 through conduit 142 to heat exchanger 143 where the
volatile, ilows tluough pipe 123 to stripper 124. In
stripper 124 the secondary condensate is contacted with
primary effluent is in indirect heat exchange relation with
drocarbon mixture, e.g., ammonia and hydrogen sulfide,
monia, and light hydrocarbons separates from C4 and
ñows through conduit 125 to conduit 119 and to means
heavier hydrocarbons and flows through conduit 148 to
conduit 149, ammonia removal means 159, and conduits
109 and 108 to secondary 110 decontaminator as previous
the condensate from separator 147 flowing to heat ex
stripping gas, eg., hydrogen-containing gas from separa
changer 143 through pipe 150.
tor 147 ñowing through conduits 148 and 167 or a mix
From heat exchanger 143 the primary etliuent ilows
ture of gas from separator 147 and hydrogen-containing 65 through conduit 144 to cooler 145 where the primary
reformer ygas ñowing to stripper `124 through conduits
eñiuent is cooled to a temperature at which C4 a-nd heavier
137, 154 and 167.
hydrocarbons are condensed under the existing pressure.
'Ihe overhead from stripper 124 comprising a major
The condensed and uncondensed portions of the primary
portion of C4 hydrocarbons and lighter hydrocarbons to
effluent flow from cooler 14S through conduit 146 to gas
gether with hydrogen and substantially all of the hydrogen
liquid separator 147. In separator 147 the uncondensed
derivatives of contaminants present in the nitro genous hy
portion of the primary effluent comprising hydrogen, am
168 for removal of ammonia and then through conduit
169 to means for removing hydrogen sulñde (not shown)
3,071,542
10
ly described hereinbefore. The C4 and heavier hydro
duit 213 to cooler 214.
In cooler 214 the secondary
carbons, hereinafter designated primary condensate, ñow
effluent is cooled to a temperature at which at the exist
from separator 147 through pipe 15o to heat exchanger
ing pressure, C4 and heavier hydrocarbons are condensed.
The cooled secondary effluent flows from cooler 214
through conduit 215 to gas-liquid separator 216.
In gas-liquid separator 216 the uncondensed portion
of the secondary effluent comprising hydrogen and C1 to
C3 hydrocarbons and a portion of the hydrogen deriva
143 `as previously described. From heat exchanger 143
the primary condensate flows through pipe 151 to stripper
152.
In stripper 152. a major portion of the C4 and lighter
hydrocarbons together with residual amounts of hydrogen,
hydrogen sulfide, and ammonia is taken overhead through
tives of contaminants in the secondary feed such as am
pipe 153 to means 170 for removal of ammonia and then
through conduit 171 to -an absorber where the overhead
is contacted with an absorbent for C4 hydrocarbons.
A minor portion of the bottoms flows through a re
monia, separates from the condensed portion of the
secondary eñiuent. Ihe uncondensed portion of the
secondary eflluent ñows from separator 216 through
boiler comprising pipe 164, heat exchanger 16S and pipe
166. The balance, and majo-r portion, of the bottoms
then through conduit 282 to an absorber (not shown)
Where the uncondensed secondary eñiuent is contacted
with a mixture of hydrocarbons to be decontaminated.
In the absorber light hydrocarbons are extracted from
the uncondensed secondary eiiiuent while oxygen and
deposit precursors are extracted from the hydrocarbon
mixture to be decontaminated. Prom the absorber the
uncondensed secondary efliuent flows to the refinery fuel
system.
The condensed portion of the secondary eiiiuent sep
arated in gas-liquid separator 216 from the uncondensed
ñows through pipe 163 to a` reforming or other catalytic
reaction unit employing a catalyst sensitive to more than l
p.p.m. of nitrogen. In other words, the bottoms of strip~
per 152 contain not more than `l p.p.m. of nitrogen.
The ñow sheet presented as FIGURE 3 is illustrative of
the hydrodecontamination of a hydrocarbon mixture con
taining more than 25 ppm. of nitrogen wherein the con
densate from the gas-liquid separator is fractionated in a
splitter to give an overhead containing C5 and lighter hy
conduit 217 to means 231 for removal of ammonia and
drocarbons and dehexanized bottoms or a bottoms contain
secondary effluent flows from separator 216 through
ing C6 hydrocarbons as controlled by local conditions.
Thus, a hydrocarbon mixture containing at -least 25 p.p.m.
of nitrogen, for example, a thermally cracked naphtha,
pipe 213 to the suction side of pump 219.
The con
densed secondary effluent, Le., secondary condensate, is
discharged by pump 219 into pipe 220x The secondary
condensate flows through pipe 22d to heat exchanger
hereinafter designated nitrogenous feed, is drawn from a
source not shown through pipe 29@ by pump 2431. Pump 30 212 as described hereinbefore. From heat exchanger
212 the secondary condensate ñows through pipe 221 to
261 discharges the nitrogenous feed into pipe 292 at a
splitter 222. In splitter 222 an overhead comprising
pressure sufficient to force the nitrogenous feed through
hydrogen and C1 to C5 hydrocarbons together with all
the downstream equipment. The nitrogenous feed ñows
or a portion of C6 hydrocarbons depending upon local
through pipe 202 to heat exchanger 2113 Where the nitro
genous feed is in indirect heat exchange relation with the 35 operating demands together with the residual ammonia
and hydrogen sulfide is taken overhead through conduit
eiiiuent from the secondary decontaminator flowing there
223 to cooler 224. In cooler 224 the overhead is cooled
from through conduit 210. From heat exchanger 2&13 the
to a temperature at which C4 and heavier hydrocarbons
nitrogenous feed llows through pipe 294 to coil 20S in
are liquid. From cooler 224 the splitter overhead tiows
In heater 266 the nitrogenous feed is heated to a 40 through conduit 22S to accumulator 226. From ac
cumulator 226 the uncondensed splitter overhead flows
reaction temperature such as set forth hereinbefore.
furnace or heater 206.
The heated nitrogenous feed hows from heater 26o
through pipe 2537 to secondary dccontaminator 2%. At
some point in pipe 297 intermediate to heater 2% and
to decontaminator 2% hydrogen-containing gas contain
ing as little ammonia as practical is mixed with the
heated nitrogenous feed in amount to provide about 5G()
to about 2500 s.c.f. of hydrogen per barrel of nitro
genous feed. A suitable hydrogen-containing gas for
through conduit 262 to the refinery fuel gas main. The
condensed splitter overhead ñows .from accumulator 226
through pipe 227 to the suction side of pump 228. Pump
228 discharges the condensed splitter overhead into pipe
229 through which the condensed splitter overhead ñows
to splitter 222 for use as reflux.
That portion of the
condensed splitter overhead in excess of requirements
for reñux in splitter 222 is diverted through pipe 23€)
this purpose is the overhead from gas-liquid separator 50 under control of valve 231 to pipe 232 and light naphtha
storage, further processing, distribution, etc.
257 flowing therefrom through conduits 258 and 252,
A minor portion of the bottoms of splitter 222 flows
means for removing ammonia 269 and conduits 261 and
to a reboiler system comprising pipe 2.33, heat exchanger
209.
234 and pipe 235 or any other means can be employed
The mixture of nitrogenous feed and hydrogen-con
taining gas containing little or no ammonia, i.‘e., not more 55 for maintaining a temperature in sp-litter 222 at which
hydrocarbons having iive to six carbon atoms, as de
than about 0.02 percent by volume cr 20G ppm. based
sired, are volatile. The balance, and major portion, of
upon the nitrogenous feed, iiows downwardly through
the splitter bottoms substantially devoid of ammonia
the catalyst bed in secondary decontaminator 2%’. The
flows from splitter 222 through pipe 236 to the suction
catalyst in secondary decontaminator 208 is one having
hydrogenating capabilities combined with the capabil 60 side of pump 237. Pump 237 discharges into pipe 238
through which the splitter bottoms flows to coil 239 in
ties of hydrodecontaminating, i.e., hydrodesulfurizing
heater 240. While the splitter bottoms are substantially
and hydrodenitrogenizing hydrocarbon mixtures. Illus
devoid of ammonia and hydrogen sulfide the nitrogen
trative of such catalyst is that described hereinbefore.
content thereof is nevertheless considerably greater than
The effluent of secondary decontaminator 251-3, herein
after designated secondary eiiiuent, ñows therefrom 65 1 ppm. Accordingly, the splitter bottoms having a ni
trogen content up to about 140 ppm. is mixed with
through conduit 210 to heat exchanger 2113 where the
about 50 to about 95 parts by volume of a mixture
secondary elliuent is in indirect heat exchange relation
of hydrocarbons having a low nitrogen content such
with the nitrogenous «feed as described hereinbefore.
that when mixed with the splitter bottoms in the propor
From heat exchanger 203 the secondary efliucnt ñows
through conduit 211 to heat exchanger 212 where the 70 tions set forth hereinbefore the nitrogen content of the
mixture is not greater than about 7 ppm. A suitable
secondary effluent is in indirect heat exchange relation
low nitrogen mixture of hydrocarbons, designated ni
with the condensed hydrocarbons liowing from gas-liquid
trogen-free hydrocarbon mixture, is straight run naphtha
separator 216 through pipe 218 to pump 219 and thence
through pipe 220 to heat exchanger 212. From heat
containing not more than about 0.5 ppm. of nitrogen.
exchanger 212 the secondary eiiiuent ñows through con 75
The nitrogen-free mixture of hydrocarbons, i.e., con
‘3,071,542
11
taining not more than about 0.5 p.p.m. is drawn from a
source not shown through pipe 241 by pump 242 and
discharged into pipe 243 at a pressure higher than the
pressure in pipe 238.- The nitrogen-free hydrocarbon
mixture flows through pipe 243 to heat exchanger 244
where the nitrogen-free hydrocarbon mixture is in in
direct heat exchange relation with effluent from primary
decontaminator 249 flowing through conduit 250. From
heat exchanger 244 the nitrogen-free mixture of hydro
overhead and flows through conduit 271 to the‘ refinery
fuel main. The condensed splitter overhead flows through
pipe 272 to the suction side of pump 273. Pump 273 dis
charges the splitter overhead condensate into pipe 274
through which the splitter overhead condensate flows to
splitter 266 for use as reflux.
Splitter condensate in ex
cess of that required for reflux in splitter 266 is diverted
through pipe 275 under control of valve 276 to further
processing, e.g., separation of C5 and C6 and isomeriza
intermediate
carbons flowstothrough
pump 237
pipeand
245totoheater
a point
240,in The
pipe mix 10 tion thereof, storage, distribution, etc.
The major portion of the splitter bottoms containing
ture of splitter bottoms and nitrogen-free hydrocarbon
mixture, hereinafter designated primary feed, tion/s
through pipe 238 to coil 239 in heater 240'. In heater
not more than l ppm. of nitrogen iiows from splitter
266 through pipe 250 to a reformer unit (not shown)
as feed thereto. A minor portion of the splitter bottoms
240 the mixture is heated to a reaction temperature with 15 flows through a reboiler comprising pipe 277, heat ex
in the range of about 600° to about 850° F. From coil
changer 273 and pipe 279 or other means for heating the
239 the heated primary feed iiows through conduit 21136
minor portion of the splitter bottoms to a temperature
to primary hydrodecontaminator 249. At a point in
such that the components of the aforesaid splitter over
conduit 246 intermediate to heater 240 and to decontami
head are volatilized.
nator 249 hydrogen-containing gas, eg., hydrogen-rich
reformer gas is mixed with the primary feed in an amount
to provide about 250 to about 2500 s.c.\f. of hydrogen
per barrel of primary feed to provide a primary feed
mixture.
A further embodiment of the present invention is illus
trated by the flowsheet FIGURE 4. A nitrogenous hydro
carbon mixture (as defined hereinbefore) is drawn from
a source not shown through pipe 301 by pump 302 and
discharged into pipe 303 at a pressure sufficient to drive
The primary feed mixture ñows downwardly through 25 the nitrogenous hydrocarbon mixture through the equip
primary decontaminator 249 which is charged with parti
ment intermediate to pump 302 and to secondary decon
cle-form solid hydrogenating and hydrodesulfurizing and
taminator 309. From pump 302 the nitrogenous hydro
hydrodenitrogenizing catalyst such as a mixture of oxides
carbon mixture ñows through pipe 303 to heat exchanger
of cobalt and molybdenum. The reaction products, des
304 where the nitrogenous hydrocarbon mixture> is in
ignated primary efliuent, flow from primary decontam 30 indirect heat exchange relation with the secondary eñiuent
inator 249“ through conduit 250 to heat exchanger 244
iiowing from secondary decontaminator 309 through
where the primary effluent is in indirect heat exchange
conduit 320. From heat exchanger 301i the nitrogenous
relation with the nitrogen-free hydrocarbon mixture as
hydrocarbon mixture îlows through pipe 305 to coil 306
described hereinbefore. From heat exchanger 244 the
in heater 307. In heater 307 the nitrogenous hydro
primary efliuent flows through conduits 251 and 252 to
heat exchanger 253 where the primary effluent is in in
carbon mixture is heated to a reaction temperature with
in the range of about 600° to about 850° F. From heater
direct heat exchange relation with the primary condensate
iiowing from pump 264 through pipe 265. Fromv heat
exchanger 253 the primary etlßluent iiows through conduit
through pipe 30S to conduit 332 and thence to secondary
307 the heated nitrogenous hydrocarbon mixture iiows
decontaminator 309.
_
254 to cooler 255 where the primary efliuent is cooled t0 40
In conduit 332 the heated nitrogenous hydrocarbon
a temperature at which under the em'sting pressure C4 and
mixture is mixed with hydrogen-containing gas in amount
heavier hydrocarbons are condensed. The cooled primary
to provide about 500 to about 2500 s.c.f. of hydrogen
efiiuent flows from cooler 255 through conduit 256- to
per barrel of nitrogenous hydrocarbon mixture. A hydro
gas-liquid separator 257. In gas-liquid separator 257 the
gen-containing gas for this purpose can be hydrogen-rich
uncondensed portion of the primary eñiuent separates
reformer gas flowing through conduit 331 from a source
from the condensed portion of the primary efiiuent. The
not shown at the pressure greater than the pressure in
uncondensed portion of the primary effluent, designated
recycle gas, Hows from separator 257 through conduits
258 and 259 to means 260 for removing ammonia. The
recycle gas substantially devoid of, i.e., containing not
more than about 0.02 percent by volume of ammonia
secondary decontaminator 309.
Hydrogen-containing
gas from stripper 32l flowing therefrom through conduits
325 and 326 to means 327 for the removal of ammonia
and thence through conduit 328 under control of valve
329 to compressor 374- and conduit 375 to conduits 331
iiows from means 260 for removing ammonia through
and 332 is likewise suitable. A mixture of both of the
conduits 261 and 209 to conduit 207 for admixture with
aforesaid hydrogen-containing gases can be used. The
the nitrogenous hydrocarbon mixture as described here
mixture of nitrogenous hydrocarbon mixture and hydro
inbefore.
55 gen-containing gas iiows through conduit 332 to secondary
The condensed primary effluent, designated primary
decontaminator 309. The aforesaid mixture iiows down
condensate, ñows from separator 257 through pipe 263
to the suction side of pump 264. Pump 2’4 discharges
the primary condensate into pipe 265 through which the
wardly through secondary decontaminator 309 which
contains a bed of catalyst having hydrogenating, hydro
' desulfurizing, and hydrodenitrogenizing capabilities. From
primary condensate iiows to heat exchanger 253 where 60 secondary decontaminator 309 the reaction products,
the primary condensate is in indirect heat exchange rela
designated secondary eñluent, flow through conduit 310
tion with the primary efiiuent as hereinbefore described.
to heat exchanger 304 where the secondary effluent is in
From heat exchanger 253 the primary condensate flows
indirect heat exchange relation with the nitrogenous hy
through pipe 2655: to splitter 266.
rocarbon mixture as described hereinbefore. From heat
In splitter 266 the temperature is maintained to take (i5 exchanger 304 the secondary effluent ñows through con
overhead‘through conduit 267 a splitter overhead com
duit 3M to heat exchanger 312 where the secondary ef
prising hydrogen, C1-C4 hydrocarbons and C5 and C6
fluent is in indirect heat exchange relation with secondary
hydrocarbons dependent upon other‘facilities, eg., for
condensate flowing from gas-liquid separator 316 through
isomerizing the C5 and C6 hydrocarbons. ’ The splitter
pipe
317 to pump 31S and thence through pipe 319 to
overhead flows through conduit 267 to cooler 263` where 70
heat exchanger 312'. From Yheat exchanger 3‘12 the
the splitter overhead is cooled to a temperature at which
secondary eiiluent flows through conduit 313 to cooler
C4 and heavier hydrocarbons 'are liquid. Fromv cooler
3M where the secondary efliuent is cooled to a tempera
26S the cooled splitter overhead flows through conduit
269 to accumulator 270. In accumulator ‘270 the uncon
ture at which7 under the existing pressure C4 and heavier
densedsplitter overhead separates from the liquid splitter 75 hydrocarbons are condensed. From cooler 314 the cooled
3,071,542
13
14
secondary efiiuent flows through conduit 315 to gas
primary decontaminator 346 hydrogen-containing gas is
liquid separator 316.
ln gas-liquid separator 316 the uncondensed secondary
The uncondensed secondary effluent, designated primary
mixed with the primary feed to provide about 250 to
about 2500 s.c.f. of hydrogen per barrel of primary feed.
A `suitable hydrogen-containing gas is stripper overhead
‘ñowing from stripper 335 and/ or separator overhead
stripping gas, leaves separator and ñows by Way of con
duits 333, 334 and 372 to stripper 335 and primary
and 361 respectively to means 363 'for removal of am
eñiuent separates from the condensed secondary effluent.
ydecon‘tarninator 346.
tlowing from separator '316 through conduits 358-, 334
»momia and thence through conduit 363 »to compressor
364 and conduit 365 to conduit 345’.
'
The condensed secondary effluent, designated secondary
condensate, ilows from separator 316 through pipe 317
10
to the suction -side of pump 338. Pump 31S discharges
into pipe 319 through which the secondary condensate
The mixture of primary feed and hydrogen-containing
gas, i.e., primary feed mixture hows through conduit 345
to primary decontaminator 346. Primary decontaminator
346 is charged with a particle-form solid hydrogenating
ñows to heat exchanger 312. `In heat exchanger ‘312 the
and hydrosulfurizing and hydrodenitrogenizing catalyst,
`secondary condensate is in indirect heat exchange relation
with the secondary effluent as described hereinbefore. 15 eg., a mixture of oxides of cobalt and molybdenum. The
primary feed mixture flows downwardly through primary
From heat exchanger 312 the secondary condensate flows
through pipe 320 to stripper 321.
decontaminator 346. The eñiuent of primary decontami
ln stripper 321 the secondary condensate is contacted
nator 346, i.e., primary effluent, flows through conduit
347 to heat exchanger 343 where the primary effluent is
reformer gas iiowing from conduit 331 through conduit 20 in indirect heat exchange relation with the nitrogen-free
hydrocarbon mixture as described hereinbefore. tFrom
347 under control of valve 348. A stripper overhead
heat exchanger 343 the primary efiiuent flows through
comprising hydrogen, ammonia, hydrogen sulñde and a
conduit 348 to heat exchanger 349 where the primary
major portion of Ci, and lighter hydrocarbons flows
effluent
in indirect heat exchange relation with the
through conduits 325 and 326 to a means 327 for removal
with stripping gas such as hydrogen-containing gas, eg.,
of ammonia and thence through conduit 370 to an ab 25 condensate (primary condensate) flowing from separator
353 through pipe 35S. From heat exchanger ‘349 the
sorber not shown where the stripper overhead is contacted
primary eiiiuent flows through conduit 350 to cooler 351.
`with a hydrocarbon mixture to extract C4 and heavier
In cooler 351 the primary efliuent is cooled to a tempera
hydrocarbons from `the stripper overhead and to extract
ture at which under the existing pressure C4, and heavier
water and deposit precursors from the hydrocarbon miX
ture. The stripper o-verhead iiows from the absorber to the 30 hydrocarbons are condensed. fFrom cooler 351 the cooled
primary effluent flows through conduit 352 to gas-liquid
reñnery fuel gas main.
separator 353. In separator 353 the uncondensed primary
A portion or all of the stripper overhead can be di
eiiiuent comprising hydrogen and C1 to C3 hydrocarbons
verted from conduit 376 through conduit 323 under con
flows through conduit 354 to means 377 for removal of
ltrol of valve 329 to compressor 374. `Compressor `374
discharges the stripper overhead through conduits 375, 35 ammonia and thence through conduit 37 3 to an absorber
not shown for recovery of light hydrocarbons in hydro
331 and 332 for admixture with lthe nitrogenous hydro
carbon mixture to ‘be treated and removal of water and
carbon mixture as described hereinbefore.
deposit precursors `from the hydrocarbon mixture to be
A minor portion of the stripper bottoms hows through
treated. From the absorber the uncondensed primary
a reboiler comprising pipe 322, heat exchanger 323 and
pipe 324 or `any other means whereby a temperature is 40 eiiluent flows :to the refinery fuel main.
The condensed primary eiliuent, i.e., primary conden
maintained in stripper 321 at which the aforedescribed
overhead is produced.
The balance, and major portion, of the stripper bottoms
sate, flows through pipe 355 to heat exchanger 349 where
the primary condensate is in indirect heat exchange rela
tion with the primary effluent as described hereinbefore.
flows from stripper 321 through pipe 336 to the suction
side of pump ‘337. Pump 337 discharges into pipe 338i. 45 From heat exchanger 349 the primary condensate ilows
through pipe 356 to stripper 335'. In stripper 335 the
The stripper lbottoms ‘ñowing through pipe 338 contain
primary condensate is contacted with a stripping gas, eg.,
not more than 140 p.p.m. of nitrogen. At some point in
hydrogen-containing gas, for example, gas from separator
pipe 338 the stripper bottoms is mixed with a hydrocarbon
316 and is heated to -a temperature at which hydrogen,
mixture having a low nitrogen content, i.e., not more than
about 5 p.p.m. of nitrogen in the proportion of about 50 50 ammonia, hydrogen sullide, Clto C3 `and a major portion
of the C4 hydrocarbons are volatile. In other words, an
to about 95 parts of low nitrogen hydrocarbon mixture,
designated nitrogen-free hydrocarbon mixture, to about
overhead comprising hydrogen, ammonia, hydrogen `sul
fide and a major portion of the C4 and lighter hydro
carbons is taken overhead. The stripper overhead flows
primary decontaminator feed naphtha containing not more
than 7 p.p.m. of nitrogen. A suitable nitrogen-free hydro 55 from stripper 335 through conduit 337 to conduit 35d;
50 to about 5 parts of ystripper bottoms to provide a
carbon mixture is a straight run naphtha containing `.about
2 p.p.m. of nitrogen.
Such a nitrogen-free hydrocarbon mixture is drawn from
a source not shown through pipe 341 by pump 342 and
to a means 377 for removal of ammonia. and thence
through conduit '378 to an absorber not shown. A por
tion yor all of the stripper overhead is diverted from con
mixture flows through pipe 330 to heat exchanger 343
where the nitrogen-free hydrocarbon mixture is in indirect
heat exchange relation with primary efliuent flowing from
primary decontaminator 346 .through conduit 347. ‘From
ammonia.
duit '357 through conduit 358 under control of valve 359
discharged into pipe 330. The nitrogen-free hydrocarbon 60 to conduit 361 and thence to means 360 for removal of
A m-inor portion of the bottoms of stripper 335 flows
through a reboiler Ácomprising pipe 366, heat exchanger
367 and pipe 363 or any other means for maintaining
heat exchanger 341-3 the nitrogen-free hydrocarbon mixture 65 the temperature in stripper 335 required to produce the
aforedescribed overhead. The major portion (the bal
flows through pipe 3441 to pipe 338 where it is mixed With
ance) of the stripper bottoms containing not more than
the stripper bottoms in the proportions described herein
1 ppm. of nitrogen flows through pipe 369 to a reformer.
A further embodiment of the present invention is illus
The primary feed ñows through pipe 338 to coil 339 70 trated in FIGURE 5. In FIGURE 5 the ñowsheet illus
before to provide a primary feed con-taining not more than
about 7 ppm. of nitrogen.
in heater 340 where the primary feed is heated to a reac
trates the use of the hydrogen-containing gas recovered
tion temperature within the range of about 600° to »about
850° F. The primary feed flows from heater 340 through
conduit 345 to primary decontaminator 346, At some
point in conduit 345 intermediate to heater 340 and to 75
from the effluent of the secondary decontaminator in the
primary deeontaminator after removal of ammonia from
the uncondensed portion of the secondary efliuent. Thus,
a nitrogenous mixture `of hydrocarbons, as defined here
3,071,542
15
inbefore, is drawn yfrom a source not shown through pipe
ondary >condensate is in indirect heat exchange relation
401 by pump 402. Pump 402 discharges the nitrogenous
with the secondary efiiuent as previously described herein.
From heat exchanger 413 the secondary condensate ñows
through pipe 425 to splitter 426. In splitter 426 a tem
perature is maintained at which residual hydrogen, hydro
gen derivatives of nitrogen and sulfur, C1 to C5 hydro
carbons with or without C6 hydrocarbons dependent upon
hydrocarbon mixture into pipe 403 at a pressure suñì
cient to push the nitrogenous hydrocarbon mixture
through the equipment downstream of the pump. The
nitrogenous hydrocarbon mixture flows through pipe 403
to heat exchanger 404- where the nitrogenous hydro
the local auxiliary facilities (e.g., isomerizing facilities)
carbon mixture is in indirect heat exchange relation with
are taken yoverhead and C6 and heavier hydrocarbons
the secondary efñuent fiowing from secondary decontami
nator 409 through conduit 411. The nitrogenous hydro lO form a bottoms. The aforesaid overhead is taken from
splitter 426 through conduit 427 to cooler 428 Where the
carbon mixture containing more than 25 p.p.m. of nitrogen
splitter overhead is cooled to a temperature at which C4,
ñows from heat exchanger 404 through pipe 405 to coil
and heavier hydrocarbons are liquid. From cooler 428
406 in heater 407. In heater 407 the nitrogenous hydra
the splitter overhead flows through -conduit 429 to ac
carbon mixture is heated .to a reaction temperature within
the range of about 600° to about 850° F. From heater
497 the heated nitrogenous hydrocarbon mixture ñows
cumulator 430. In -accumulator 430 the uncondensed
`splitter overhead separates from the condensed splitter
through conduit 408 :to secondary decontaminatm- 409. At
overhead and is vented through conduit 431 to the re
ñnery fuel gas main. The splitter overhead condensate,
Le., condensed splitter overhead, is drown from accumu
secondary decontaminator 409 hydrogen-containing gas,
such `as reformer gas, flowing from a source not shown 20 lator 430 through pipe 432 by pump 433. Pump 433 dis
charges the splitter condensate into pipe 434. A portion
through conduit 410 is mixed with the heated nitrogenous
of the splitter condensate iiows through pipe 436 under
hydrocarbon mixture in the proportion of about 500 to
control of valve 437 to splitter 42o for use as reflux.
about 2500 s.c.f. per barrel of nitrogenous hydrocarbon
The bal-ance of the splitter condensate, in excess of that
mixture to form a secondary charge mixture.
a point in conduit 408 intermediate to heater 407 and to
The secondary charge mixture flows downwardly 25 required for reflux in splitter 426, ñows through pipe 435
to further processing or storage and/or distribution as
through secondary decontaminator 409 in contact with a
hydrogenating, hydrodesulfurizing and hydrodenitrogen
light naphtha.
izing catalyst such `as a mixture of oxides of cobalt and
A minor portion of the bottoms of splitter 426 flows
through a reboiler comprising pipe 438, heat exchanger
molybdenum.
As described hereinbefore, conditions in
30 439 and pipe 440 or any other suitable means for heat
secondary decontaminator 409 are as follows:
ing a portion of the splitter bottoms to a temperature re
Table V
quired to maintain a temperature in splitter 426 at which
the aforedescribed splitter overhead is produced.
The balance, and major portion, Aof the splitter bottoms
Catalyst: 2_3 percent cobalt oxide, 9-16 percent molybde
num oxide.
Feed: Nitrogenous hydrocarbon mixture-66 p.p.m. nitrogen.
35 containing not more than about 140 ppm. nitrogen is
Broad
Temperature, ° F ..... __
60G-850
Pressure, p.s.i.g____,_
S.c.f. Hz/barrel of feed
Space velocity, v./hr./v.
200~1,000
50G-2, 500
1-10
Preferred
675-775
drawn from splitter 426 through pipe 441 by pump 442
and discharged into pipe 443. In order to produce lan ef
fluent from primary decontamin'ator 446 containing not
40G-800
more than 1 p.p.m. of nitrogen under the conditions
800-1, 000 40
set forth hereinbefore it is necessary that the hydrocarbon
2. 5-5
charge to primary decontaminator 446 contain not more
The effluent from secondary decontaminator 409, desig
nated secondary eñiuent, ilows through conduit 411 to
than about 7 ppm. of nitrogen. Accordingly, the splitter
bottoms containing not more than about 140 p.p.m. of
nitrogen is mixed with about 50 to about 95 parts by
heat exchanger 404 where the secondary eñiuent is in 45 volume 'of a mixture of hydrocarbons boiling preferably
indirect heat exchange relation with the nitrogenous hy
in the gasoline range containing an amount of nitrogen
drocarbon mixture «as `described previously herein. From
such that when mixed with the splitter bottoms in the
heat exchanger 404 the secondary eiiiuent flows through
proportions set forth hereinbefore the mixture contains
conduit 412 to heat exchanger 413 where the secondary
not more than about 7 ppm. of nitrogen. Suitable pro
e?liuent is in indirect heat exchange relation with second 50 portions of splitter bottoms having various nitrogen con-`
ary condensate drawn Áfrom gas-liquid separator 417 ñow
centrations and nitrogen-free hydrocarbon mixtures to
ing through pipe 422 to pump 423 and discharged into
be mixed therewith to provide a primary feed containing
pipe 424 by pump 423. From heat exchanger 413 the
not more than about 7 ppm. 0f nitrogen are listed in
secondary effluent flows through conduit 414 to cooler
Table VI.
'
415 where the secondary effluent is cooled to a tempera 55
Table VI
ture at which C4 and heavier hydrocarbons are condensed.
The cooled secondary effluent Hows from cooler 415
Splitter Bottoms
Nitrogen-Free Hy
through conduit 416 to gas-liquid separator 417. In gas
liquid separator 417 the uncondensed secondary eñiuent
separates from the condensed secondary effluent. The 60
uncondensed secondary effluent ñows through conduit
418 to means 419 for removal of ammonia. The sec
ondary eiiiuent containing not more than about 0.02 per
cent by volume ammonia, now designated primary hydro
drocarbon mixture
Primary
Feed,
P.p.n1. of Volumes
N
Ppm. of
P.p.m. of Volumes
N
N
‘ 140
5
0.2
95
7. 2
100
50
45
25
12
5
1()
5
2. 0
2.2
5. 0
05
90
95
80
50
6. 8
7.0
7.0
genating gas, ñows from means 419 for removal of am 65
20
2. 5
7. 0
monia through conduit 420 to conduit 421 where it is
50
2.0
7.0
mixed with the mixture of the bottoms of splitter 426 and
the nitrogen~free hydrocarbon mixture to «form a primary
A suitable nitrogen-free hydrocarbon mixture or diluent
charge mixture as described hereinafter.
The condensed secondary effluent iiows from gas-liquid 70 is' straight-run naphtha containing not more than 5.0
separator 417 through pipe 422 to the suction side of
pump 423. The condensed secondary effluent, designated
secondary condensate, is discharged by pump 423 into
pipe 424 through which the secondary condensate Hows
to heat exchanger 413.
ppm. of nitrogen. Accordingly a nitrogen-free hydro
carbon mixture containing nitrogen not in excess of that
Which when mixed with the splitter bottoms in a propor
tion within the range of 95 to 50 volumes per 5 to 50
In heat exchanger 413 the sec 75 volumes> of splitter bottoms to form a primary feed con
3,071,542>
17
taining not more than about 7` p.p.m. of» nitrogen is
drawn from a source not shown «through pipe 447 by pump
In splitter 463` an overhead comprising hydrogen, am
monia, hydrogen sulfide, C1 to C4 hydrocarbons, and C5
and C6 hydrocarbons dependent upon auxiliary facilities
448. Pump 448 discharges the nitrogen-free hydrocarbon
mixture or diluent into pipe 477 at a pressure at least
locally available is taken through conduit~ 464. For ex
ample, in some reñneries it can be preferred to take all
equal to that in pipe 443. The nitrogen-freerhydrocarbon
mixture or diluent flows through pipe 477 to heat ex
of- the C5 and C6 hydrocarbons overhead for isomeriza
tion. Therefore, the splitter overhead can be- character
changer 449 Where the nitrogen-free hydrocarbon diluent
is in indirect heat exchange relation With primary eflluent
ized as comprising hydrogen, ammonia, hydrogen sulfide,
ñowing from primary decontaminator 446 through con
duit 451. From heat exchanger 449' the nitrogen-free
hydrocarbon diluent ilows through pipe `450 `to pipe 443i.
In pipe 443 the nitrogen-free hydrocarbon diluent is mixed
and hydrocarbons the major portion of whichy are C5 and
lighter hydrocarbons. The overhead from splitter 463
flows through conduit 464 to cooler 465 where the C4 and
heavier hydrocarbons are condensed. From cooler 465
with the splitter bottoms to form a primary feed con
the splitter overhead flows .through conduit 466 to ac
taining not more than about 7 p.p.m. of nitrogen. The
cumulator 467. In accumulator 467 the uncondensed
primary feed flows through pipe 443 to coil 444 in heater 15 splitter :overhead is vented to the -reñnery fuel gas main
445. In heater 445 the primary feed is heated to -a re
through conduit 468. The condensed splitter overhead
action temperature within the range of «about 600° to
is drawn from accumulator 467 through pipe 469 by
about 850° F. The heated primary feed ñows from heater
pump 470, Pump 470 discharges the condensed splitter
445 through conduit 421 to primary decontaminator 446.
overhead into pipe 471. A portion of the- condensed
At some point in the conduit 421 hydrogen-containing gas 20 splitter overhead required for reflux flows through pipe
containing not more than about 0.02 percent ammonia,
471 under control of valve 472 to splitter 463i. The bal
e.g., hydrogen-containing gas from gas-liquid separator’
ance flows through pipe 473 to storage, further processing,
417 is mixed with the primary feed in .a proportion Within
or distribution as light naphtha.
the range of about 250 to about 2500 s.c.f. per barrel
A minor portion of the splitter bottoms is circulated
of primary feed to form a primary charge mixture. The 25 through a re-boiler comprising pipe 474, heat exchanger
primary charge Vmixture flows downwardly through
475’ and pipe `476 or any other suitable means for heating
primary decontaminator 446 in which the conditions are
the minor portion of the bottoms to a temperature suchu
within the ranges set forth in Table VII.
that the temperature required to produce the aforede
scribed splitter overhead is maintained in splitter Á463.
Table VII
30
The balance, and major portion, of the splitter bottoms
Catalyst: 2 to 3 percent cobalt oxide, 9 to 16 percent molyb
flows from splitter 463 through pipe 480 to a reformer
denum oxide.
unit (not shown) employing a nitrogen-sensitive reform
ing catalyst. It will be noted that the splitter bottoms
Feed: Not more than about 7 p.p.m. of nitrogen.
Broad
` Preferred
Temperature, ° F ___________________________ __
Pressure, p.s.i.g _______________________ __
__
600- 850
20G-l, 000
Hydrogen, Set/b, of Primary Feed____
250-2, 500
___
675-775
40G-50C
ñowing through pipe 477 contains not more than l` p.p.m.
35 of nitrogen.
In view of the foregoing discussion of the illustrative
40G-G00
examples of the present invention it is manifest that the
present invention provides for hydrodecontaminating a
reformer charge stock containing moreV than 2.5 p.p.m. of
The efñuent from primary decontamina‘tor 446, desig 40 nitrogen in the presence of a catalyst having hydrogenat
nated primary eñiuentjlows through conduit 451 to heat
ing and decontaminating capabilities such as a. mixture of
oxides of cobalt and molybdenum under conditions of ’
exchanger `449 -where the` primary eñiuent is in indirect
heat exchange relation with the nitrogen-free hydrocarbon
temperature, pressure, space velocity and hydrogen to
diluent or mixture as_previously described herein. From
charge stock ratio to produce la secondary condensate.
Space Velocity, v./hr./v _____________________ __
l-
l0
2. 5-5 0
heat exchanger 449 the primary eñluent flows through 45 The secondary condensate is stripped of volatile hydrogen
derivatives of the contaminants originally present in the
conduit 452 to heat exchanger 453 where the primary. ef
fluent is in indirect heat exchange relation with the primary
charge stock» to provide a partially decontaminated second
condensate flowing from gas-liquid separator 457.` From
heat exchanger 453i, the primary ei'liuent` ilows through
about 140 p.p.m. of nitrogen. The secondary decontam
ary decontaminator bottoms containing not more than
conduit 454 to cooler 455 where the primary effluent is. 50 inator bottoms containing not more than about 140
cooled to a temperature such that Cr and heavier hydro
p.p.m. of nitrogen is mixed lwith reformer charge'stock‘ to
carbons are condensed. From cooler 455 the cooled,
provide a primary decontaminator feed containing not
primary eñcluent flows through conduit 456 to gas-liquid
more than about 7> p.p.m. of nitrogen. The primary de
separator 457. In gas-liquid separator 4'57 the uncon
contaminatorV feed isV then hydrodecontaminated in the
densed primary eñluent is separated from the` condensed 55 presence of a catalyst having hydrogenating‘and decontam,primary effluent.
inating capabilities and in the presence of hydrogen“
In separator 457 the uncondensed pri-mary eiiluent. is
containing gas containing not more than aboht 0.02 per
cent ammonia under conditions of temperature, pressure,
of ammonia and thence through conduit 479 to an ab
space velocity and ratioof hydrogen to primary decontam
sorber (not shown) where it is contacted with -a hydro 60 inator feed to produce, after fractionating the primary
carbon mixture which absorbs Cr and heavier hydro
decontaminatorV condensate, a reformer feed containing“
vented through conduit 458 to means 478l for removal
carbons. At lthe same time the uncondensed primary ef
less than about l- p.p.m. of nitrogen.
‘
fluent removes Water and deposit precursorsfrom the hy
The hydrodecontaminating'conditions used in both the- '
drocarbon mixture. The uncondensed primary ei’ñuent
secondary and primary decontaminators are within the
ilows from the aforesaid absorber to the reñnery fuel gas 65 limits set forth in Table IV.
mam.
~
The condensed portion ofthe primary effluent desig
nated primary condensate flows from gas-liquid4 separator
457 through pipe 459 to heat exchanger 453` Where the
primary condensate is in indirect heat exchange relation 70
Table IV
Broad
Preferred
with the primary eiliuent yas described hereinbefore. From
heat exchanger 453i the primary condensate is drawn
through pipe 460 by pump 461 which discharges the
primary condensate into pipe 462. The primary con
densate ilows «through pipe 462 ‘to splitter 463.
75
Temperature, ° F-.
Pressure, p.s.i.g. ___
Sei. Hz/bbl. of feed"
_-
600 to 850
200 to 1,000
250 to 2,500
675 to 775
400 to S00
400 to 1,000
Space velocity, v./hr./v __________________ __
1 to 10
2 5 to 5.0
3,071,542
19
20
,We claim:
1. In the method of preparing a hydrocarbon mix
ture boiling in the boiling range of naphtha and Vcon
taining in excess of 25 p.p.m. of nitrogen for reforming
in the presence of nitrogen-sensitive particle-form solid
reforming catalyst wherein a first static bed of nitrogen
with the aforesaid second naphtha to provide a liquid
primary hydrodecontaminator fed containing not more
than 7 p.p.m. of nitrogen.
2. The 4method set forth in claim 1 wherein the gaseous
fraction separated from the secondary hydrodecontamina
tor efliuent is treated to remove ammonia, and wherein at
and sulfur-insensitive particle-form solid hydrogenating
least a portion of the so-treated gaseous fraction is in
catalytic material is established in a secondary hydrode
contaminator, wherein a second static bed of nitrogen
troduced into the secondary hydrodecontaminator.
and sulfur-insensitive particle-form solid hydrogenating
catalytic material is established in a primary hydrodecon
fraction comprising ammonia, hydrogen sulfide, hydrogen,
3. The method set forth in claim l wherein a gaseous
taminator, wherein a first naphtha containing in excess
of 25 ppm. of nitrogen is introduced into said secondary
and C1 to C3 hydrocarbons is separated from the primary
hydrodecontaminator effluent, wherein ammonia is re
moved frorn the aforesaid gaseous fraction, and wherein
hydrodecontaminator and intimately contacted therein
the aforesaid »gaseous fraction after said removal of `am
with the aforesaid first static bed of hydrogenating cat
monia is introduced into said primary hydrodecontamina
alytic material at a liquid hourly space velocity in the
range of about 1 to about l0, wherein hydrogen is intro
duced into said secondary hydrodecontaminator and flows
tor.
4. The method set forth in claim 1 wherein the gaseous
fraction separated from the secondary hydrodecontamina
tor effluent is treated to remove ammonia, wherein at
therethrough at a rate in the range of about 500 to about
2500 s.c.f. per barrel of the aforesaid first naphtha, where 20 least a portion ofthe so-treated gaseous fraction is in
troduced into the secondary hydrodecontaminator, where
ing a gaseous fraction comprising arñ'monia, hydrogen
sulfide, hydrogen, and C1 to C3 hydrocarbons is separat
in hydrodecontaminating conditions of temperature in the
range of -about 600° to about 850° F. and a total pres
sure of about 200 to about 1000 p.s.i.\g. are maintained
in the aforesaid secondary hydrodecontaminator, wherein
' ed from the primary hydrodecontaminator efliuent, where
a» secondary hydrodecontaminator efHuent comprising am 25 in said gaseous fraction is treated to remove ammonia,
and wherein the so-treated gaseous fraction is introduced
monia, hydrogen sulfide, hydrogen, and C1 and heavier
into said primary hydrodecontaminator.
~\\
hydrocarbons is withdrawn from said secondary hydro
5. The method set forth in claim 1 wherein a gaseous`
decontaminator, wherein the whole of said secondary hy
fraction comprising ammonia, hydrogen sulfide, hydrogen,
drodecontaminator effluent is mixed with a second naphtha
having a relatively low concentration of `organic nitrogen 30 and C1 to C3 hydrocarbons is separated from the primary
hydrodecontaminator effluent', wherein said gaseous frac
compounds and containing also impurities in the form of
tion is treated to remove ammonia, and wherein said treat
organic sulfur compounds to form a primary hydrodecon
ed gaseous fraction and reformer make-gas are introduced
taminator feed, said second naphtha being a major por
into said primary hydrodecontaminator.
tion of the normally liquid hydrocarbons of said primary
hydrodecontaminator feed, wherein said primary hydro 35 6. The method set forth in claim 1 wherein a gaseous
fraction comprising ammonia, hydrogen sulfide, hydrogen,
decontaminator feed is introduced into the aforesaid pri
and C1 to C3 hydrocarbons is separated from the primary
mary hydrodecontaminator and intimately contacted
hydrodecontamin-ator efñuent, wherein at least a portion
of the reformer make-gas is mixed with the aforesaid sep
therein with the aforesaid second static bed of hydro
genating catalytic material at a liquid hourly space ve
locity in the range of about l to about 10 in -the presence
of hydrogen in a ratio in the range of about 250 to about
2500 s.c.f. per barrel of naphtha, wherein hydrodecon
taminating conditions of a temperature in the range of
about 600° `to about 850° F., and of a total pressure in
arated gaseous fraction to provide diluted primary hydro
decontaminator gaseous fraction, wherein a gaseous frac
tion comprising ammonia, hydrogen sulfide, hydrogen, and
C1 to C3 hydrocarbons is separated from the secondary
hydrodecontaminator efliuent, wherein said separated gase
the range of about 200 to about 1000 p.s.i.g. are main 45 ous fraction of secondary hydrodecontaminator efliuent is
mixed with a portion of said diluted primary hydrodecon
tained in said primary hydrodecontaminator, wherein a
taminator gaseous fraction to provide diluted secondary
hydrodecontaminator gaseous fraction wherein the bal
ance of the aforesaid diluted primary hydrodecontamina
primary hydrodecontaminator effluent comprising am
monia, hydrogen sulfide, hydrogen,>and C1 and heavier
hydrocarbons is withdrawn from said primary hydrode
contaminator, wherein said primary hydrodecontaminator
eñiuent is separated into a plurality of fractions, wherein
one of the aforesaid fractions is a C54- hydrocarbon frac
tion of substantially reduced nitrogen content, and where
in said C54- hydrocarbon fraction is reformed in contact
with nitrogen-sensitive particle-form solid reforming cat
alyst to produce reformer eñluent comprising C1 and
heavier hydrocarbons and hydrogen, wherein said re
former effluent is separated into reformer recycle gas
and reformer make-gas each comprising C1 to C3 hydro
carbons and hydrogen, and reformate comprising C4 and
heavier hydrocarbons, and wherein at least a portion of
50 tor gaseous fraction is treated to remove ammonia, where
in said treated diluted primary hydrodecontaminator gase
ous fraction is introduced into said primary hydrodecon
taminator, wherein said diluted secondary hydrodecon
taminator gaseous fraction is treated to remove ammonia,
55 and wherein at least a portion of said treated diluted
secondary hydrodecontaminator gaseous fraction is in
troduced into said secondary hydrodecontaminator.
7. ’Ihe method set forth in claim 6 wherein at least
one of the group consisting of the diluted primary hydro
60 decontaminator gaseous fraction and the diluted second
said reformer make-gas is introduced into said secondary
hydrodecontaminator, the improvement which comprises
separating the aforesaid secondary hydrodecontaminator '
eiiiuent into :at least one gaseous fraction comprising am 65
ary hydrodecontaminator gaseous fraction is treated to
remove hydrogen sulfide.
References Cited in the file of this patent
UNITED STATES PATENTS
monia, hydrogen sulfide, hydrogen and C1 to C3 hydro
carbons, and a liquid fraction comprising C4 and heavier
hydrocarbons containing not more than 140 p.p.n1. of
nitrogen, and mixing the aforesaid liquid fraction only
-2,728,710
2,767,121
2,937,134
Hendricks ____________ __ Dec. 27, 1955
Watkins ______________ __ Oct. 16, 1956
Bowles ______________ __ Mayv 17, 1960